Studies on Monoterpene Glucosides and Related Natural Products. XXXIX. Biogenetic-type Transformation of Geniposide into Plumieride

Abstract

A biogenetic-type transformation of geniposide (9) into plumieride (1) was carried out. The tetraacetyl-geniposide (12) prepared from geniposide (9) via 10-dehydrogeniposide (10) was subjected to sensitized photooxygenation to give tetraacetyl-gardenoside (13). Oxidation of the allylic hydroxy group of 13, followed by condensation of the resulting aldehyde (23) with ethyl acetoacetate afforded tetraacetyl-13-dehydroplumieride (24). This compound (24), on reduction followed by acetylation, gave a pair of epimers, 28 and 29, of which the major one (28) was deacetylated to give plumieride (1).